Check circuits



Dec. 7, 1954 B. D. HoLBRooK x-:TAL

CHECK CIRCUITS 9 Sheets-Sheet 1 Filed Feb. l2. 1953 A TTORNEV Dec. 7, 1954 B. D. HOLBROOK ETAL CHECK CIRCUITS Filed Feb. 12. 1953 Wwmbl hmmm@ @Mh 250m B. D. HOLBROOK W. A. MAL THANER gai., VAUGHAN /N I/E/V TORS ,a f2/7m ATTORNEY Dec 7, 1954 B. D. HoLBRooK ETAL CHECK CIRCUITS Filed Feb. 12. 1953 9 Sheets-Sheet 3 B. D. HOL BROOK INVENTORSI 'M A. HAL THA/VER H. E. VAUGHA/V GLA., 244% ATTORNEY sa sheets-sheet 4 AAA B. D. HoLBRooK ETAL CHECK CIRCUITS AAA Dec.l 7, 1954 Filed Feb. 12. 195:5

- a. o. H01. a/eoofr WVU/70H5: c .4. MA1. rHANE/e By Hf. muc/MN MWD/,Lm

Afro/aww Dec. 7, 1954 Filed Feb. l2. 1953 B. D. HOLBROOK ETAL CHECK CIRCUITS 9 Sheets-Sheet 5 B. D. HOL BROUK /AHA/TO/-- A. MAL THANER H. E. VAUGHAN A TTORNEV Dec. 7, 1954 B. D. HoLBRooK ETAL CHECK CIRCUITS 9 Sheets-Sheet 6 Filed Feb. 12. 1953 B. D. HOL BROOK /NI/ENTORSf W. A. MALTHANER H. E. VAUGHAN y mqml ATTORNEY Dec. 7, 1954 B. D. HoLBRooK ET AL 2,696,599

CHECK CIRCUITS BV wq@ ATTORNEY Dec. 7, 19.54 B. D. HoLBRooK ETAL 2,696,599

CHECK CIRCUITS Filed. Feb. 12. 1953 9 Sheets-Sheet 8 RESET coz/v ma B. D. HOLBROOK /Nl/ENTORSf W. A. MALTHANER H. E. VAUGHA'N A 7'7'ORNE y 9 Sheets-Sheet 9 B. D. HOLBROOK E-'I'AL CHECK CIRCUITS Dec.' 7, 1954 Filed Feb. 12. 195s m @Px o. H01. noox myn/Tons.- mA. mL THA/mv By n.5. muc/MN 5 Q ATTORNEY inl that office.

United StatCSPant n CHECK CIRCUITS Bernard D. Holbrook, Madison, William A. Malthaner, New'Providence, and Henry E. Vaughan, Chatham, N. J., assignors to Bell Telephone Laboratories, Incorv'pora'tetL New York, N. Y., a corporation of New York Application February 12, 1953, serial No. 336,562l 1 1 ls Claims.V (ci. 340-147) y. v

This invention relates to check circuits and, morepar- `ticularly, to such circuits wherein the informationto'be'r checked comprises a succession of coded pulses appearing yon a Asingle wire in time sequence.;

In telephone systems, the subscriber placing the call will ldial the number ofthe party called, which number lcomprises both a designation of the called office, such -as CHels'ea 3,' and the directory number vof the called .party In general telephone practice, lthe designation of the called oice is utilized by the calling office lto assign a proper out trunk while Vthe directory number tubes.

2,696,599 Patentedl Dec. 7, 1 9754 .ICC

It is another object of'this` invention to `provide air vimproved circuitfor checking the registers in which the code isstored during-the checking operation.

A further object of this invention is to enable thel checking of large information messages employing manyy digits on an (x-t-ay)outof'n basis in an .efficient manner whereables each four-element gas tube ineach registerin suc- -ces'sion,ring of. aiparticulargasrtube to store. a pulse f in` a register being `thus controlled by the concomitant appearance at that'tube ofv a voltagefrom the digit steerringcircuit, a voltagesfrom the time slot commutator circuit, and a pulsein the signalsv being received.I

Eachiregister tube isA connected to a single common 4 counting'circuit which counts the number of tubes red in of the called party is transmitted to that called oice over .this trunk. Advantageously, the called number is transmitted in a 2-out-of-5 code in which each digit of the'number iis represented by this code.

In application Serial No. l58,2l8,led-April 26, 1950,

each register. Atv the end of a digit interval, an inspect pulse isy applied to an `error detecting circuit causing it to ascertain the condition of the counting ,circuit whichis' so arranged that there isa uniquer condition for a proper and plausible code.

of W. A. Malthaner and H. E. Vaughan, there isdescribed a telephone signaling system in which the called number is transmitted to the called oflice by pulse code modulated signals on a 2-out-of-5 basis." In such 'a system, it

A, is advantageous to check the code at the' called oflice-to ascertain that it is plausible and, if it is not, send back a signal requesting the calling oice to transmit'the code again. In the system described in the above mentioned application, the code is registered in electron discharge devices in registers foreach digitfin the code, and an individual check circuit is utilized for each digit register.` This requires'a large number of check circuits, thereby increasing the cost and complexity of the system. Further, the employment of a single check circuit foreach digit register would be prohibitive of the'use of the circuit inidigital computers'and other systems wherein it is desired to check information messages employing more than just the four digits generally utilized in telephone signaling systems of the ,type describedin the above mentioned application.

Further, in various electrical ,circuits and systems, ythe Ainformation message 4may comprise a large number of digits which are coded lin variations o f an x-out-of-ncode wherein an acceptable code is not simply one in which lthere arex signal pulses but in which theremay be, for f example, x or any multiple of x signal pulses, or x land x" @pulses and any number of pulses whichis` uy greater .thanx or x', .where yis a specified number and a is any number.' i

A general object ofthis invention is to provide-antimments includes a number of` active code elements or sig- ,nals vequal to a ,speciednumber orset ofynumbers, in` ,creased by any multiplegof another specified number.

This vmay be expressedby saying that a code is `acceptable it it is in the form l where x is any number or set of numbers, a is a multiplier, f y .any specitiednumber and n the total number ofcode elements, where `lnjvth'e speciclinstance wherein y=0, thecode is an x-out-of-n code. It is, therefore, a speciiic'objectof'this Y ,invention to ,provide an improved circuit for checking the plausibilty of an xl-out-of-n code appearing in `time sequence. o

If this unique condition is present, indicating that the digit storedin that particular register 'during that-digit interval is plausible, no action is taken by he check circuit. If, however, an implausible anderroneous codefhas beeny registered, the counting circuit will not lhave counted to its unique condition, and the. error detecting circuit will cause operation of a recycling circuit which` willresetthe registers, .the digit steering Vcircuit and the time slot commutator circuit and cause anerror fsignal to be transmitted back to the prior circuitry advising prises'a binary counter employing a plurality `of tubes -and the unique condition ofr that counter occurs ywhen the outputs -of thosetubes indicate a count of the appropriate numberT of register tuberings. Thisoutput may advantageously be the binary-numbery equivalent to the decimal number x in the x-out-of-n code or may advantageously fbeonly a portion ofvthat output if n is not equal to 2, `where a is any integer. rThus, if the code to :bechecked "1 yis a 3-out-of-'6 code, Vthe output of the counter circuit need not be the completeV binary number 011,.which .is.the

binary equivalent'of the decimal 3, but need` be onlyll.

the least signicant digits of` the number, as .that combination is unique ofthepossible outputs for that code.r Similarly, if a2-out-of-5 code is to be checked, only the least register ltubes.

signiticant` digits -l0,\i.e., considering `the code to be X10,

.. need be utilized as they are unique from binary. 0, .(000) lto binary'5, (101).v i

It is, therefore, a feature of thisinvention thata countingcircuitbe commonto all the registers -fand thatthe counting circuit .havea unique condition indicating that an acceptable Land vplausiblenumber of pulses have ,been stored in each register `circuit through ythe ring ofl the Itis a further feature of this invention that thisfunique condition be ascertained by, an` error `detecting circuit which inspects the 7condition of the counting circuit after each; digit interval and in appropriate cases advises a verror signalv output `.to be generated.

recyclingcircuit to reset the circuit land :to .cause an It is a furthernfeature of this invention that the'countfingl circuit count in an.y incomplete binarycode.

It isa vstill further` feature ofthis invention that" the inspect pulse applied to the errordetectingcircuit to enable it toinspect. the condition of the counting circuit Qbe' derived' from the :last discharge "device of the' time slot commutator circuit through a delay circuit assuring suticient time vto elapse for the ring of a register discharge. device inthe last time slot and thecounting thereof before ythe inspection of the'counting circuit.v

"theseand various other features theref511.121) be gained A. 'complete vur'iderstanding'of this inventionfandl of "ir-aecomo 3 from consideration of the following description and the accompanying' drawing, 'in which:

Fig. l is a simplified schematic representation, mainly I in block form, ot' one specific illustrative embodiment of thisdnvention, A

l Fig. 2 'sja time" graphshowingithe"Ioccurrence'fiof various pulses vdii`r"i1'ig"the'pefrationof thecircuitf-of Fig." 1;

Figs. 3 through" 8 vare detailed's'cl'ie'maticvr representagons 1of a circuit `rin accordance" with 'the' embodiment of 1g. v Fig. '9' is a detailed-"schematic representation of'fa control circuit for supplyingfthetimingfor synchronizing pulses toi the circuit ofFig.' 3;;and Fig.I 10 4is'akey-diagram 'showing 'the 'arrangementof Figs.'3 through' 9.

Turning now `to` `vthe drawing,I Ein "the"specific1V illustrative embodiment ofithisA invention rep'rkesen'tedy in Fig.' '1, digit registe'rs: 10 are 'providedf'each"incorporatingn "f four electrodeg'aseous discharge devices"11,"whi'chl may 'f 'be thev hot cathode* thyr'atrons, 'suchvas" the RCA'j5'696 and other thyrat'rons. "Ther information "rnessaget'be *checked kcomprises aser'ies'of :coded'pulses-13t=inf time "sequence applied bythe' input`Iead14of-the check circuit to an AND circit 15 for eacli register' 10. 'I-'heoutputs of a digit's'teering circuit 17-a`re also applied to the AND ,circuits 15 and determinewhich VAND circuit-15,' and therebywhich register '10, is 'chosenfor a particular digit `in the: infomation message. The'digit steering circuit isadvanced one step for each digit'of' the information ymessage by digit stee`ring"pulses 18v applied thereto at the beginning of each digit, as clearly `seen inthe-"time plots Aof Fig. 2 whereincoded pulses 13 comprising'the decimal 'message 379 are depicted.

j The output of the AND circuits 15 arefapplied to one controlelectrode 20v of eachof the gaseous-'tetrodes- 11. The other control electrode' 211 of e'achi tetrode 11=fis connected'to aiti'mesl'ot sampling commutator'circuit423 which advances 'once'A each time"`slotinfeveryfdig-'iejon Yapplication"thereto of time slot 'enabling'pulses 24,2 thus each output lead 25 Afrom the time slot sampling commutator'circuit has' a 'voltage' applied toit in succession for each digit of the"`mes`sage "being checked.y `=A.`par- ^`ticular` tetrode 11 will iire,"'therefore,' when` the proper f pulse r13, 'output from ldigit steering `circuit 1'7,' and'o'utput from'tirne slot samplingcommutator circuit 23` are f' present. Thus, if a pulse 13 appears in the second time gvslot inthe iirst digit-'of a code' message,"indicating a code l intheA digit, the second tetrode '11 'of the lA register will /iire and only that tetrode.

Each'register'l is connected" to a single counting cir- "cuit", 28"s0' that Whenever a device ina'ny register flires, Qa pulseV is applied to the counting circuit '28. Circuitf'28 ","fco'unts the number o f devices 11l firedI in 'each'register 10,

' being reset after 'each digit has vbeen' registered' Iby a r j `counterV reset pulse 29. However;intheiperiod'between f't'he completipnof f the pulses of a"'digit andbefore-the v Y"counter reset pulse 29, an inspect pirlserlfis applied to i error detecting .circuit '32" causing kthat circuitfto 'look "at the counting circuit'528. If'the' countin'g'circuit I28 has counted the proper number of register de ce'o'u'tputs, i. e., "fjhasy counted to c if an :c 'out-'of-n 'code' is'fbeing checked, ff'the errordetecting circuit'will take noA action. f However, "j if anyother number' is present in the counting circuit-128, "then the error detecting circuit 3 2 willenabl'e a'recycling circuit '34 causing' an errorfoutput pulse 35 tobe'g'enerated vand also enabling a reset circuit 36 which resets j 'the' registers'. l'thefrdigit steering circuit"'17, `and the ""time slot samplingcommutato'r circuit323.

Countingcircuit 28 willQthus individually'bount the number ofdischarge l(.ievices operated"injfeaclrlo'the N registers being'- inspected and then'rese'tjaftefeach digit interval. It is, therefore, apparent'thaf'Nythenumber i of digits in the i codei being checked mayib'e averyj large Vnumber .Withno' increase iri'lthc" Complexity ofthe check- .'ing "circuit Thus,L in accordancei' with' dnef feature of Hthis y invention checking of a"mes'sage coniprising any number of 'Coded digits isffa'cilely andjexpeditiouslyattained by the er'npl'oyment"V Off' common checking'apparaf`tus,"includi`ng'the c'unti'n'g circuit 28 and error detecting circuit 32. v v,

Turning'now t o 1 igs 3 8, th'er'elis shown a detailed schematic ,representation of the "specic -illustr' at'ive"`em b o'dirnen` t lof'thislinveritioii;depictedinfFig.'V 1,. In" Figs. A3-8 for purposes of exposition, it has' been a's'snied'that the information message to be checked comprises only three digits-eachon-a 2-out-of-5v .basisfbutfit..is.1o-be understood that this specic embodiment of this invention is capable of checking messages employing much 5 larger numbers of digits which may be on any x-out-of-n basis. As seen in Figs. 3-8 the cathodes of each tetrode 11 in a given register lllare'all connected across an inductor 38 so that V.operation of--anyftube in that register produces a pulse across it. 'The'inductors 38 in the 10"three"regist'ersf10"are connectedtog'e'ther by an 4or #circuit comprising diodes 39? and the output40 of the or circuit isappliedto the'1 control electrode of an inverter tube 41 seen in Fig.- 3. Thus, when any register tube 11 operates a negative pulsel 42 appears at the out- 15 putofltheinverlter' 41. 'These'n'egative pulses-42 are applied to the two stage binary counter circuit 28 comprising a doubletriode`tube"45'-anda double triode tube 46. The normally negative plate 48 of tube 4S is conxnectedfto theleft 'grid yof a-doub`le triode tube- 5 0 of 20. the error detectingfcircuit'32; the normally positiveplate 5510i ltube f 46y isfsimilarly connected to :the right grid of tube 50. If in the i-rstdigi t interval, none `ofrxthefA if'registertubes 11-had` fired, tubes 45 and 46'would remain .=n'ormal.` f -At the end'ofthisintervalthe inspect pulse 31 v 'is-applied tothe inputvcircuitof both halves of,y error =jdetectingtube 50. The inspect pulse 31 isderived from the circuit," as described/furtherbelow, and;A is applied f'to'the 'gridsfof tube 50 throughfdelay circuits-49am' 52 'for reasonsfurther sc t forth below. Thisvpulse 31,:'incom- 30 binati'on with the positive voltage from' platei`51, causes a pulse 54to appear ontheplate resistor =55' of. the error detecting tube 50 which in turn ,operates the recycle toggle circuit which comprisesgthe-double triode 56., .j A positive voltage on either lead from plate '48 o rfSl-v will 'cause the yrecycle toggle circuitj34 tofoperatewhenfthe finspect pulse 31 occurs-at the endvof a. digit-interval. The above conditions describeXt-he" operationy of fthe circuit if -no 'code pulsesare received duringfthe' digit .ingterval. i Fromthe above descriptionand l.the 'following 40 table, it is thought that theoperation of -this circuit will be apparent:

Asican readily be seen` from theabovet'able and from' the circuit, a p ,ulse 54 is .appliedto the recycletoggley circuit 34 for 1each final condition ofthe binary counting circuit 28"except for a countjindicating'that`-the'codeis a plausi- .'ble* one',l Whichinl this case indicates-'thattwoout `of ive i" possible' pulses have been received. 0 AThefpossible outputs of' the recycling 'tube' "56V are 6 applied 'to ther t wo'control 'grids of ythe ytwolsections flotfa double triode?gatetubef,seenfin lFig. 8. The V"condition of'tub'e60I will,therefore,depend yonV the 'condition of the recycling tube 56. If no pulse 54- isfappl-ied G jtohe' :recycling circuitf, nothing will voccurin tube '6G v4as we'are only"considering at this time the trst ydigit of "the -code being checked. f, however, this were the ."last digitof'the code', then a'pulse 72,"ind1icating-that 'thecorfnplete'co'de has vbeen checked, as ydescribed fur- ,.ther "below,"would `alsoy be applied to the grid ofl the righthand sectionv of tube "69 which' would co'nductindi- -`cating that -th'e' complete code lstored inthe registertubes l 11* i's` 'plausible and transmit aco'de'jreceived pulse 61 to the work Vcircuit 62. If, however,'anirnplausible code has been received-'and'--recycling circuit 34 has been ,enabled by a pulse 54, then 4the left-hand side `of tube 60 will conductand transmit a'reset'command lor error 1pulse l63 'to 'a reset monopulser'niin the`reset-'circuit"36, seen in Fig. 6. Operation of the resetlmonopulser 64 enables voltage regulator'l't'ubes 65 and 66. Tube 65 resets-the digit and commutator tubes inv the digit steering 'circuit 17 and time slot commutaton circuitI 23, respectlv'el byinterruptingthe' voltages 'applied' to vthe fj plates thereof, and tube'i66 vsimilarly'r'esets each'of register' tubes' '111. Operation of the reset Icircuitalso causes a pulse 68 to be delivered back to""the'"tans assesses mitting circuit advising it to reset the circuits supplying the various synchronizing pulses .for this check circuit. The reset command or errc` pulse 63 is also sent. back to the prior circuit that has received the code and advises it that the code was in error; pulse 63 thus is thezerror output pulse 35 depicted in the simplied block diagram of Fig. l. In a telephone signaling systernof the type described in the yabove mentioned,Malthaner-Vaughan application, the error pulse 63 will advise the circuit that has received ythe transmitted -signal from a' distant oilice that the code was in error and the receiving circuit would then send a signal to the transmitting office requesting it to transmit the code again. i y

Similarly, after each correct code has been received,

which is indicated by a complete counting of the digit steering circuit 17 `to a complete code tube 70, seen kin Fig. 6, a complete code pulse 71 may advantageously be returned to the prior circuit.. An output pulse 72 from the other side of` tube 70 is applied `to. the grid of the right-hand section of tube r60, seenin Fig. 8, to cause transmission of a codereceived pulse 61 to tthe work circuit 62, as described above.

Turning now to Fig. 9, there is depicted one control circuit for providing the check` circuit of Figs. 3-8 with the properly synchronized pulses. The control circuit may advantageously comprise an oscillator tube operated on application of a start pulse from the prior circuit, which tube supplies a sinusoidal output 91, best seen in Fig. 2, to ya squaring tube 92, the sinusoidal output beingsuch Vthat one cycle occurs 4during each time slot in a digit. Tube 92 provides squared timing pulses.75,'also seen in Fig. 2, to both sides of a gatingtube 94.k From the cathode of the leftsection of gate tube `94 are taken the commutator sampling pulses 24, providedr that a complete code pulse 71 is not present to stop the operation of this circuit. As can readily beseen infFig.` 2, these time slot commutator sampling pulses 24 zoccurat the instant of the trailing edge of the squared timing pulses 75 and thus in the middle' of each time slot.` The digit steering pulses 18 are taken from the cathode of the right section of tube 94 and occur when that section has been enabled `by an output pulse 80 fromthe last tube of the time slot commutator-circuit 23.

code that has the property thata given set of received ycodeelernents 4is acceptable if and only ifthe number 1. Vof .active code elements or signals is'equal `to a specied Turning back to Figs. 3-8, pulse 80 ris generated byV the last tube in the timeslot commutator circuit, 7 Corn., and indicates that the last time -slot has occurred. l This pulse 80 is applied to each of Ithe last tubes 11 in the registers -10 and also to the error detector circuits through the delay networks 49 and 52, as described yabo've,fso that the occurrence of the inspect pulse 31 to enable the error detecting circuit 32 occurs vslightly before the 4end of the last time slot, as shown on Fig. 2. -The inspect pulse 31 is this pulse 80 delayed by networks 49 and 52. By utilizing this delay sufcient timeis allowed for a register tube 11 in this-last time slot to re and generate a pulse to be counted by the counting circuit 28. i 1- 1 After each digit has been checked, the counting-circuit is reset by a counter reset pulse 29 generated `by the reset counter tube 74. Enablement of this tube ccurs such that the reset counter pulse 29 is generated after the inspect pulse 31 and 'before the commencement of the next time slot. This tube is enabled by the pulse 80 of the last tube ofv thetime slotfcommutator circuit 23 and by the rising edge of a squared timed pulse 75. These two enabling pulses are applied `to a gating tube 79, seen in Fig. 6, Vwhich then producesan enabling output 77 causing ring of the reset counter tube74. Advantageously, the digit steering pulses 18 are generated by the right-hand section of tube 94- infthe control circuit of Fig. 9 on the occurrence of the 7 Com. output pulse 80 and the rising edge of a squaredtiming pulse 75. Thus, the digit steering circuit `17 is stepped and the counter circuit 2S reset substantially at the same time, just before or at the beginningvtof the vfirst time slot of the next digit, as shown in Fig. 2.

Advantageously, the plates of register-tubesl 11 are each connected through leads 76 tothe work vcircuit 62 so that the code registered intheregister tubes 11 can be passed on to the work circuitfon receipt bythe work circuit 62 of a code received pulse 61 from gate tube 60. Such work circuit may` compriseregistering apparatus for storing the code number and,'when this.

embodiment of this invention is employed in a telephone number or set of numbersincreased by any multiple .of another specied number. It is ybelieved that-othertypes .of codes thatmay be checked in 1accordance :with this |invention will be apparent from; a consideration of two specific codes. in certain systems and circuits .codes are rendered checkable .by theadditionof 'a check signal to each digit so that the tot-al number of signals in the digit is even. Such a code is No. of De- 'vices 11 red in each -Register 10k Binary-Check The code to be checked is thus of the form Where x,=0, y=2, and a--any number. `In such a code the counting circuit 28 would count the number of. pulses -42 received, corresponding to the numberbf register bits` or .devices v11 operated in eachregister 10 in `succession, andintheinterval betweenI the completion :of the pulses'. of a digit andbefore .the counter-reset pulse 29, .the inspect pulse 31 applied to the error. detecting circuitwould causethat circuit to. look atthe counting circuit.. yThe error detecting Vcircuit 32 would ythen only .enable .the recycling .circuit 34 causing an error output 35 to be generated, as best seen in Fig. l,\if. the counting circuitr 28 has counted to other than 4an even num- -fber of pulses. As Lhe counting circuit 23 is common to all the registers 1l), in accordance with `one aspect V-of th1s.1nvent|ion,.this will -be repeated for. each-digit ofthe informationmessage. s

i .Thus itv 's to be understoodl thatUt-his inventioni is not limitedto the checking of an.information `message of any particular number of digits, the three-digit message .described above with reference to an x-out-.of-n code being merelyillustrative as this invention is particularlyadapted tothe checking of messages oftveryl many coded digits.

, -Thechecking of `alarge digit message, regardless of the specific form of` the digit code, is accomplished by. circults inaccordance with this invention asdescribed above; `the countlng, error detecting, recyclingVand reset circuits .maybe as above described even though a much larger message is` vbeing checked.. Thus, in accordance with i a `feature of this invention, multi-digit messages can be 4ifoimation in theV binary form' checked. inra single. and economical circuit.

g Another type ofl codewhich `can readily be V1n `a circuit `1n Vaccordance with forniv Achecked this inventionis of the v l 71((vxor Ixf.)-I-tty)#out-of-nl t 'and may be exemplified by a code in-.which'only in- XXXX01X is acceptable." This means that the system lin which this code-is employed requires fthat only -codes corre- "sponding to thedecimallnumbers 2, 3, 10, 11,118, 19, i etc., Vbe acceptable.- t In such a code. x=2, x'=3, and

91:8.` This specific code vmay alsobe :readily checked 1n` a circuit in accordance with our invention by yapplying each digit to a digit register 10 and counting the ,..iiiber ofgd vices 11. operated, in a. registenby the i" I counting A"(:irc'ui`ti28f 'the' circuit 29 being common 1 to^-a1l 4 theirgistersflofin accordance"Withj'one feature Iofj'this finver'i'tionfV The error detectingicircuit' 32 is 'thengso'jconlnectedf to the'counting'bircuit :23"that it is enabled if:

of' the elements of the counting circuit V28 jcounting the vnumber of register vbit devices 11 operated Y j n-` each digitregisterl 10 'by a`single common counting 'circuit 28, and causingthc error detecting circuit 32 to 1k"belena'bled'onother than the desired count or counts i of Ythe countin'gcircuit 28.

Further, it i's to be understood that While the register f bit devices 11 have been'ds'closed as being gaseous discharg'e'devices, any bistable device, including transistors, AND gate coincidence circuits,` etc.,'rn'ay be employed in the registers 10.A

'fTherefore, it is to be understood that the above de-` scribedarrangements "are merely illustrative of the ap- "plication of the principles of this invention and that numerous Yother arrangements may be, devised by those skilled in the art without departing from the spirit and f scope of the invention.

What is claimed is:

l. A circuit for checking codedv information comprising an information message ofV Ndigits'codedin a code L having the property that a set .of received code elements is acceptable'iil and o'nly if the number of active code elements is Yequal to atleast oneyjsjpeciiiednumber increased by any multiple of another specied number comprising a digit register for each digit of an information message to be checked, each register comprising bit registering means Afor each possible pulse of a digit, means for steering the digits ofv said message lto said 'T "registers in succession, means for enabling each bit reg- `istering means in said registers inr succession whereby said `bit registering means are operated on the concomitant operation of said steering means, said enablingv nieansl and a'puls'e in said code, means for counting the number of bit registeringmeans operated in a register, said-means comprising a single counting circuit electrically 'connected to all of said bit registeringumeans, means foi' inspecting the condition of said counting circuit after each digit" has been stored in onev of said registers, and means for resetting said circuit and transmitting an error signal if said counting circuit has counted other than a correct number of pulses in any digit in the information message.

2. A circuit for checking coded information comprisv ing an informationniessage'of' N digits coded ink a code i having the property that a set7 received "code-elements t i's'f"`ccepta"ble ifandv only ifthenumber' of active Vrcode -feler'rientfs" is fequ'al" toaty 'least one 4specified nui'jnberfinilfc'rea'sed"byf'fany multiple'iof other 'specied number comprising N vdigit registersl each* c :oir'ii'risingl bit -registering means foreachfpos'sible'pulse of ai`digit,fi`i i eans for `f-en`abling each' of4 vsaid ybit "registeringj ineari'sl .inj

tofoperate on"th`efappea`ran ce of 'afpulse in th jin said code represented byitha't bit eg" y, gvk "me'ansfor' counting Ythe 'numbefrfo'f bit` registering 'means operated in a lreigis'terf said* counting 'means comprising a singlebinary'counting circuitand` eans'suppiying a pulse tofsaid, countingcircuit'OfOpQration ,offeachf of said bit Vregist A iig ineanslin anyfofi'saidregisters;'said 'counting circuit Jhaving'ia'uniquejco'ridi nl when anactable number of pulses "h'av`bee'n iico'urited; Tiieans for inspecting the condition ofI said counting circuit 'after each digit interval,saidin'specting means comprising error4 Vdetectorf'.circuit'means "connected to-"said"f'bin,ary counting circuit and operable'to'fy produce-'anfoutput pulse on other than said uniquepondition in said counting circuit, and means for enabling said error detector ciri "digit of vthe I information messager-fand means 'responsive rese'tting said registers and enabling-in a'nsonappea'r'ance v circuit forcheckiiig"codedinformationcompris-` #possible pulse of' a'digit, means for s teeringv'thedigits jofjsaid 'message't said-registers in succession, means i tor-enabling each ybit registering means infsaid registers ""in succession whereby said bit registering means operate fon the concomitantoperation of said steering means, "said enabling" means, and a pulse `in said code, means for counting the number of bit registering means operated flin a 'r'egister,v sidimeans comprising a single counting circ'uit' electrically connected to all of said devices, vmeans v lfor inspecting the condition of said counting circuit after "a'cli digit has'been stored in said registers, and means or resettingsaid'circuit 'and-transmitting aneri'or' signal f said-counting circuit has counted other thana correct numberof Ipulses in-anydigit in said-message.

i l4.' Arcir'cuit for checking coded information ,comprising zin-information message fof N 'digits *each4 infan f' "J`c'- out'V-o`f.'(ll'code 'appearing'in time sequence 'comprising "N digitregisters each'comprising n` bit registeringmea'ns, A means for enabling cach of `saidjbitregistering"means nfs'uccessionf vto yoperate on-the--appearanceof a` pulse inf thel t-ime slot in' said code'freprcse'iited by that bit registeringmeans, meansfor counting'Y the number' of "bitregisftering means Aoperated in a register, said counting 'means -comprising a' singleI binaryv counting circuit :Tantist-means ksupplying a pulse to said 'counting circuit on .i :.ftheope'ration'of any bitl registering means, said counting circuit having a fuiiique'condition when x pulses have been counted, means for'ii'ispecting the-condition of said counting circuitl after each digitfinterval, said inspecting -means comprising' error detecting circuit means conn'ectedto'said binary countingcircuit andl operable to 'producean output pulse on other than said unique conditioninsaid'counting circuit and means for enabling said i error detector 'circuit means after occurrence of the nth "time slo'tf in each digit,E andmeansl'responsive' to said 'output from said errorfdetector circuit means 'for resetting -said registers' and said enabling meanson appearance of e'saidoutput from said error detector circuit means.

t 5.',A circuit for checking coded information' comprising an information-message of N digits' each in an x-out-of-n 'code appearing intimesequenc'e comprising N .v'di'git 'registers each 'comprising n"bitlre"gis'tering means, "m'eans for enabling each of said bit registeringl means in succession' to operate on the appearance of a pulse in tthe'time slot insaid code" represented' by' thatbit registering means; said enabling means` comprising a digit steering Vcircuitand a time 4slot Vcommutator circuitfcomf 'prising ln "discharge devices'each determinative" of' the #ffe'iiablement ofA a-'bitregistering means in a timeslot in .the code,means'for counting the number 'of bit register- "ing-means operated in aregister, said counting means comprising 'a single binary. counting circuit and means supplying .a'pulse to said counting circuit' on'the operation of each bit registering means, said counting circuit including.discharge-devices. having a unique condition when 'x pulses havebeenl counted, means for-inspecting the condition of said 'counting'circuit after each digit i interval, said inspecting means comprising error detector `circu1t-"means connected to said binary counting circuit and operable to produce an output pulse on other' than said unique condition'in said ycounting circuit and means for enabling said errordetector circuitmeans after occurrence of the nth time slot` ineach digit, said last'mentioned means including the'nth discharge device in said Ttim'e' slot 'commutator circuit and delay means between said nthdischarge device and said error detectorcircuit means, andfmea'nsrespojnsive to said output' from said 'errordetfector circuitl means for resetting said registers, said digit steeringmeans, and said time slot commutator Ameans on fappearancev ofk saidr output from said error 'detector circuit-means.

6'; kA checking'circuit in accordance Withclaim 5 wherein said error `detecting circuit comprises a plurality of discharge devices" having their grids connected" to `certain 'of -the'plates of said binary counting devices, an

enabling pulse being `provided to at least one of' said j. grids oii'- each condition of said counting devices lother jthan said 'unique condition indicating thel counting of 'x pulses.

7. A'circuitfor checking coded informationcomprismgi information message of N digits veach a 2-out-of5 code' appearing in time sequence comprising N digit registers each comprising five discharge devices, means for enabling each of said discharge devices in succession to discharge on the appearance of pulses in the time slot in said code represented by said discharge device, means for counting the number of devices discharged in a register, said counting means comprising a single binary counting circuit including a plurality of discharge devices and means supplying a pulse to said counting circuit on the ring of each register discharge device, two plates of said counting circuit devices having a unique condition when only two pulses have been counted by said counting circuit, means for inspecting the condition of said counting circuit after each digit interval, said inspecting means comprising error detector circuit means comprising two discharge devices having their grids connected to said two plates of said counting circuit devices, an enabling pulse being provided to at least one of said grids on each condition of said counting devices other than said unique condition indicating the 20 counting o f two pulses and means for enabling said error detector circuit means Iafter the occurrence of the fth time slot in each digit, and means responsive to said output from said error detector circuit means for resetting said registers and said discharge device enabling means on appearance of said output from said error detector circuit means.

8. A checking circuit in accordance with claim 7, wherein said discharge device enabling means comprises a digit steering circuit and a time slot commutator circuit comprising ve discharge devices each determinative of the enablement of a register device in a time slot in the code and said means for enabling said detector circuit means comprises the fifth discharge device in said time slot commutator circuit and delay means between said fifth discharge device and said grids of said error detector discharge devices.

References Cited in the tile of this patent UNITED STATES PATENTS Name 

